com.thinkaurelius.titan.diskstorage.idmanagement

Class ConsistentKeyIDAuthority

java.lang.Object

com.thinkaurelius.titan.diskstorage.idmanagement.AbstractIDAuthority

com.thinkaurelius.titan.diskstorage.idmanagement.ConsistentKeyIDAuthority

All Implemented Interfaces:

IDAuthority, BackendOperation.TransactionalProvider

public class ConsistentKeyIDAuthority
extends AbstractIDAuthority
implements BackendOperation.TransactionalProvider

IDAuthority implementation assuming that the backing store supports consistent key operations.

ID blocks are allocated by first applying for an id block, waiting for a specified period of time and then checking that the application was the first received for that particular id block. If so, the application is considered successful. If not, some other process won the application and a new application is tried.

The partition id is used as the key and since key operations are considered consistent, this protocol guarantees unique id block assignments.

Author:

Matthias Broecheler (me@matthiasb.com)

Field Summary

Fields

Modifier and Type	Field and Description
protected int	randomUniqueIDLimit

Fields inherited from class com.thinkaurelius.titan.diskstorage.idmanagement.AbstractIDAuthority

BASE_ID, idApplicationWaitMS, metricsPrefix, uid, uidBytes

Constructor Summary

Constructors

Constructor and Description
ConsistentKeyIDAuthority(KeyColumnValueStore idStore, StoreManager manager, Configuration config)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the IDAuthority and any underlying storage backend.
IDBlock	getIDBlock(int partition, int idNamespace, Duration timeout) Returns a block of new ids in the form of IDBlock.
List<KeyRange>	getLocalIDPartition() Returns the lower and upper limits of the key range assigned to this local machine as an array with two entries.
StoreTransaction	openTx()

Methods inherited from class com.thinkaurelius.titan.diskstorage.idmanagement.AbstractIDAuthority

getBlockSize, getIdUpperBound, getPartitionKey, getUniqueID, setIDBlockSizer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

randomUniqueIDLimit

protected final int randomUniqueIDLimit

Constructor Detail

ConsistentKeyIDAuthority

public ConsistentKeyIDAuthority(KeyColumnValueStore idStore,
                        StoreManager manager,
                        Configuration config)
                         throws StorageException

Throws:

StorageException

Method Detail

getLocalIDPartition

public List<KeyRange> getLocalIDPartition()
                                   throws StorageException

Description copied from interface: IDAuthority

Returns the lower and upper limits of the key range assigned to this local machine as an array with two entries.

Specified by:

getLocalIDPartition in interface IDAuthority

Returns:

Throws:

StorageException

close

public void close()
           throws StorageException

Description copied from interface: IDAuthority

Closes the IDAuthority and any underlying storage backend.

Specified by:

close in interface IDAuthority

Specified by:

close in interface BackendOperation.TransactionalProvider

Throws:

StorageException

openTx

public StoreTransaction openTx()
                        throws StorageException

Specified by:

openTx in interface BackendOperation.TransactionalProvider

Throws:

StorageException

getIDBlock

public IDBlock getIDBlock(int partition,
                 int idNamespace,
                 Duration timeout)
                   throws StorageException

Description copied from interface: IDAuthority

Returns a block of new ids in the form of IDBlock. It is guaranteed that the block of ids for the particular partition id is uniquely assigned, that is, the block of ids has not been previously and will not subsequently be assigned again when invoking this method on the local or any remote machine that is connected to the underlying storage backend.

In other words, this method has to ensure that ids are uniquely assigned per partition.

It is furthermore guaranteed that any id of the returned IDBlock is smaller than the upper bound for the given partition as read from the IDBlockSizer set on this IDAuthority and that the number of ids returned is equal to the block size of the IDBlockSizer.

Specified by:

getIDBlock in interface IDAuthority

Parameters:

partition - Partition for which to request an id block

idNamespace - namespace for ids within a partition

timeout - When a call to this method is unable to return a id block before this timeout elapses, the implementation must give up and throw a StorageException ASAP

Returns:

a range of ids for the partition parameter

Throws:

StorageException